Nissan’s “Steel Plan” Amping Up Lightweighting
In March 2013, Nissan Motor Co., Ltd. announced its plan to expand the use of Advanced High Tensile Strength Steel (AHSS) in to up to 25 percent of the vehicle parts (measured by weight) installed in its new production models. Nissan reported that they would make use of Advanced High-Strength Steel starting in 2017 as one of its initiatives to help reduce vehicle weight.
That plan has already begun to unfold in production vehicles as Nissan launched the 2015 Murano, which designers shaved 130 lbs. out of the redesigned model through AHSS applications for some parts. This and improved aerodymanics, which reached a 0.32 coefficient of drag compared to 0.37 in the previous model, resulted in the redesigned vehicle’s 20 percent improvement in fuel efficiency. The 2015 Murano curb weights will range from 3693 to 4025 lbs., which is less than V6-powered competitors like the Ford Eage and Toyota Venza, but little more than four-cylinder competitors like the Hyundai Santa Fe and Ford Escape.
On 12 November 2014, Popular Science named the 2015 Murano a “Best of What’s New” award winner, the magazine’s top honor given to products or technologies that represent a “significant step forward.” The all-new Murano – which resets the standard in the midsize crossover segment with breakthrough design, premium interior and purposeful technology – is part of an exclusive group of vehicles recognized in the Automotive category.
Nissan’s Steel Development
Newly adopted 1.2 Gpa advanced high-strength steel along with an increased usage of 980MPa allowed Nissan to reduce panel thickness and reduce body-in-white (BIW) mass by 6% from previous Murano.
Nissan has developed*1 1.2 gigapascal (GPa) Ultra High Tensile Strength Steel with High Formability and has employed it in the new Infiniti Q50, which goes on sale in North America in 2013. Prior to the development of 1.2GPa ultra high strength steel it had been difficult to use high tensile steels for vehicle parts with highly complex shapes. Nissan continues to be the only auto manufacturer*2 using 1.2 GPa Ultra High Tensile Strength Steel with High Formability.
With the active adoption of 1.2 GPa ultra high strength steel, which is one grade among several types of advanced high tensile strength steels, Nissan will increase the adoption rate of AHSS as far as 25 percent of the gross weight of the parts installed per vehicle. This effort will begin in 2017 and aims to reduce the weight of Nissan’s vehicles by 15 percent with corresponding body structure rationalization.
Through an optimal combination of materials, the jointly-developed*2 1.2 GPa Ultra High Tensile Strength Steel with High Formability provides greater elongation, and offers strength and high formability, to make lighter-weight steel sheets. These attributes enable it to be used for parts with complex shapes, which had been difficult to manufacture using established high tensile steels. Combined with high-precision die design and a welding process suitable for materials during the production process, the 1.2GPa Ultra High Tensile Strength Steel with Formability can now be applied to the production of more vehicle parts.
In addition, employing 1.2 GPa high tensile strength steel leads to fewer materials used per vehicle produced, and existing production lines can be used without a big modification. This results in a reduction in total cost per unit.
Under the Nissan Green Program 2016, Nissan’s mid-term environmental plan, the company is aiming for a 35 percent improvement in fuel economy compared with 2005 on a corporate average for all Nissan vehicles by the end of fiscal 2016. To that end, the extensive use of Advanced High Tensile Strength steels, including the new 1.2GPa ultra high tensile steel, will contribute to reduced vehicle weight and better fuel economy.
*1 Jointly developed by Nissan Motor Co., Ltd., Nippon Steel & Sumitomo Metal Corporation and Kobe Steel, Ltd.
*2 For use as structural body parts in cold pressing